1. Field of the Invention
The present invention relates to a steering device adapted for use in a toy car, such as radio controlled cars.
2. Description of the Prior Art
A radio controlled toy car comprises a transmitter which is to be operated by a modeler through a steering stick and a forward-reverse stick, a receiver which receives signals of radio waves from the transmitter, and servos which are operated by signals from the receiver, but translated into mechanical movements. These mechanical movements are put out from a servo horn to the model unit to be controlled. The model car having these elements can be controlled at will by manipulating a stick of the transmitter quickly or slowly, to full range of throw or half way, the movement of the servo horn is hooked up to be transmitted to, for instance, front wheel/steering of the car.
An example of a steering device for use in a toy car according to a prior art is shown in FIG. 3. The device includes cylindrical members 2, 3 having a pair of arms and disposed on the chassis 1. Both the cylindrical members 2, 3 are fixed to the chassis 1 by means of a screw 4. When the cylindrical members 2, 3 are to be fixed to the chassis 1, a spring 6 is interposed between the head 5 of the screw 4 and the upper surface of the cylindrical member 2 and the biasing force of the spring 6 is applied to the surfaces of both cylindrical members 2, 3 which are in abutment against each other. Said surfaces in abutment of the cylindrical members 2, 3 are tapered surfaces cut away in two opposite directions so that when the tapered surfaces of both the cylindrical members 2, 3 are mated completely together, both the cylindrical members will provide a rod having no clearance at the joint portions of their outer circumferential surfaces.
One of the cylindrical member 2 will be coupled to output shaft 8 of the servo 7, and the other cylindrical member 3 will be coupled to a link (not shown) to be connected to wheels.
According to the embodiment as shown according to the prior art, when the servo 7, having received a signal from the transmitter, causes the output shaft 8 to be rotated, the cylindrical member 2 will also be rotated through an angle corresponding to the rotation of said output shaft. However, since the spring 6 forcibly pushes the cylindrical member 2 against the cylindrical member 3, the cylindrical member 3 is caused to rotate together with the cylindrical member 2 to provide a necessary steering angle to a wheel.
If a wheel hits a rock or drops in a crack on a road so that the steering of said wheel is uncontrollable; and when the output shaft 8 of the servo 7 is rotated under such a condition, the cylindrical member 2 alone at the side of the servo 7 will be rotated against the biasing force of the spring 6. Because the cylindrical member 3 can not be rotated, the tapered surfaces will slip against each other, and accordingly, the servo 7 can not create a reaction force more than a predetermined value.
As is clearly seen from FIG. 3, according to the prior art, the sliding resistance between the cylindrical member 2 and 3 is adjusted by biasing the spring 6 against the top surface of one of the cylindrical members. Since the biasing force of spring 6 is variable due to inherent variation in the manufacture thereof, or the biasing force may be varied depending on how much the screw 4 is tightened, it is difficult to keep constant the sliding resistance between the cylindrical members 2, 3 for every product.
Furthermore, the requirement of a spring 6 itself causes a increase in the number of parts and makes the management of the parts more complicated.
The present invention has therefore as an object subject to solve or eliminate the problems of the prior art as above explained.
In order to solve the problems as above mentioned, there is provided a steering device for use in a toy car including an output member having integrally formed therewith a cylindrical part adapted to be coupled to the output shaft of a servo, and a pair of arms so formed as to surround the cylindrical part, and an input member having a bore placed on the cylindrical part, and a portion connected to the link for a wheel, characterized in that the side edge portions of the input member will be in abutment with the free ends of the arm of said output member.
The output torque from the servo is transmitted from the arms at the output member to the input member and provides a necessary rotary angle to the input member. However, when a wheel is in such a condition as not being able to rotate, the output torque from the servo will elastically deform said arms for the torque to be absorbed by the arms and will not forcibly move the wheel. In other words, no reaction force from a wheel more than necessary, will be transmitted to the output shaft of a servo. Accordingly, the servo will not be damaged; and since excessive torque is absorbed by the arms, a spring, as used in the prior art, will not be necessary. Furthermore since the elastic force of the arms is determined by the configuration and the material of the arms, variation of said elastic force from product to product, quite infrequent.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.